A U.S. general says the number of foreign fighters entering Iraq and Syria has plummeted in the past year.

Major General Peter Gersten said at the Pentagon on April 26 that when he arrived in Baghdad last year, some 1,500 to 2,000 foreign fighters were joining the Islamic State group every month but now it is only about 200 per month.

The general said that along with the decrease in foreign fighters joining IS, the desertion rate is also on the rise.

Gersten said the drop in new recruits from abroad and fighters leaving the group is due in part to the U.S.-led coalition's continued attacks on the IS group's cash facilities.

He said the coalition has carried out about 20 such air strikes that have destroyed as much as $800 million.

Gersten said that has led to an inability by IS officials to pay fighters and that has resulted in "a fracturing in their morale...[and] we are seeing the inability to fight."

Gersten would not give an estimate on the overall size of the IS force in Syria and Iraq.

The U.S.-led coalition has been bombing IS forces and strategic sites in Iraq and Syria since August 2014.